1. Field of the Invention
The invention relates to a rotatable roller with a roller body, having correlated therewith channels for guiding a medium therethrough for the purpose of temperature control of the roller body, the medium being, in particular, a liquid.
2. Description of the Related Art
Such rollers are used in many fields of application, for example, in the manufacture of paper, in the foodstuff industry, as well as in rolling processes of plastic or steel, for example, for continuous casting and rolling in a continuous casting process. It is known in this context to provide roller bodies with channels, extending axially in the roller and near the surface, for temperature control of the roller bodies, for example, for heating them. Such rollers, for example, are disclosed in EP 0 606 660 A1.
In the case of channels with parallel walls, which can be produced by drilling, for guiding a medium through, in particular, a heating liquid, a high consumption of heating medium is required for a laminar flow in the channel. Moreover, only the outer areas of the flow profile provide sufficient heat to the walls of the channels and thus to the roller. Inwardly positioned flow threads largely keep their heat energy, and this impairs the heat transfer efficiency.
It is an object of the present invention to provide an improvement of the channels for such rotatable rollers.
In accordance with the present invention, this is achieved in that at least one of the channels has correlated therewith a separating member so that tempering media of different consistency and/or temperature and/or flow direction and/or flow speed can flow within one channel.
According to another embodiment this object is achieved in that at least one deflecting member correlated with at least one area of the channel and acting on the medium is provided which imparts an additional flow direction to the substantially axially oriented flow of the tempering medium.
The deflecting member for this purpose is characterized by at least one deflecting area which is positioned at a slant relative to the longitudinal axis of the deflecting member.
By providing separating members in the channels, the medium flow is provided with a smaller cross-section in the channel so that the speed of the tempering medium is increased and an improved temperature transfer is ensured. Moreover, the channel divided in this way can be used simultaneously for supplying and returning the tempering medium. In this context, a division of the channel into halves, thirds or fourths (two, three or four channel portions) is advantageous. Even divisions by greater numbers are possible. It is particularly advantageous when the separating member has the shape of a multi-start helix so that a turbulence of the tempering medium can be achieved simply by means of the helical configuration. Moreover, the residence time of the tempering medium is increased as a result of the longer travel path. The turbulence, the increase of the residence time, and the speed increase caused by the channel constriction result in an optimal heat transfer.
With the embodiment according to the invention of a roller having a deflecting member arranged in at least one area of the channels, which imparts to the substantially axially oriented tempering medium flow an additional flow direction, a departure from laminar flow of the medium flowing through the channels is ensured. Turbulence results with which the volume per time unit of the tempering medium flowing through the channel or channels of the roller is reduced. This results in savings of, for example, heating liquid. But at the same time, the heat transfer to the roller is improved; a larger proportion of the heating medium comes into contact with the walls of the channels.
When the deflecting member in its mounted position has a longitudinal extension following the channel orientation, the deflecting area can extend over a large longitudinal area of the channel. The heat transfer is then improved over a large longitudinal area of the channel. When arranging the deflecting area at least in the outer portion of the deflecting member, turbulence is achieved in the areas neighboring the channel walls. The efficiency is thus especially good. In this connection, the deflecting member can have a rigid longitudinal or form a deflection area as a whole, for example, in the way a coil spring.
An especially favorable configuration results when the deflecting area imparts a rotation to the medium flowing about the deflecting member. This can be achieved, for example, by a spiral shape of the deflecting member following the longitudinal direction of the longitudinal axis.
When the deflecting areas have varying ascending gradients across the axial extension of the deflecting member, the roller areas can be loaded in a targeted way with different intensity of the tempering media.
A special advantage results when the separating members and the deflecting members are inserted into one channel wherein the separating members can be the support for the deflecting members.